package demo.cypher;

import javax.crypto.*;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;

/**
 * Created by IntelliJ IDEA.
 * User: alex
 * Date: 14.04.11
 * Time: 23:25
 * To change this template use File | Settings | File Templates.
 */
public class StringEncrypter {

    Cipher ecipher;
    Cipher dcipher;

    StringEncrypter(String passPhrase) {

        // 8-bytes Salt
        byte[] salt = {
                (byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32,
                (byte) 0x56, (byte) 0x34, (byte) 0xE3, (byte) 0x03
        };

        // Iteration count
        int iterationCount = 19;

        try {

            KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
            SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);

            ecipher = Cipher.getInstance(key.getAlgorithm());
            dcipher = Cipher.getInstance(key.getAlgorithm());

            // Prepare the parameters to the cipthers
            AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);

            ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
            dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);

        } catch (InvalidAlgorithmParameterException e) {
//            System.out.println("EXCEPTION: InvalidAlgorithmParameterException");
        } catch (InvalidKeySpecException e) {
//            System.out.println("EXCEPTION: InvalidKeySpecException");
        } catch (NoSuchPaddingException e) {
//            System.out.println("EXCEPTION: NoSuchPaddingException");
        } catch (NoSuchAlgorithmException e) {
//            System.out.println("EXCEPTION: NoSuchAlgorithmException");
        } catch (InvalidKeyException e) {
//            System.out.println("EXCEPTION: InvalidKeyException");
        }
    }

    public static void testUsingPassPhrase(String passPhrase) {

//        System.out.println();
//        System.out.println("+----------------------------------------+");
//        System.out.println("|  -- Test Using Pass Phrase Method --   |");
//        System.out.println("+----------------------------------------+");
//        System.out.println();

        String secretString = "Attack at dawn!";

        // Create encrypter/decrypter class
        StringEncrypter desEncrypter = new StringEncrypter(passPhrase);

        // Encrypt the string
        String desEncrypted = desEncrypter.encrypt(secretString);

        // Decrypt the string
        String desDecrypted = desEncrypter.decrypt(desEncrypted);

        // Print out values
//        System.out.println("PBEWithMD5AndDES Encryption algorithm");
//        System.out.println("    Original String  : " + secretString);
//        System.out.println("    Encrypted String : " + desEncrypted);
//        System.out.println("    Decrypted String : " + desDecrypted);
//        System.out.println();

    }

    public String encrypt(String str) {
        try {
            // Encode the string into bytes using utf-8
            byte[] utf8 = str.getBytes("UTF8");

            // Encrypt
            byte[] enc = ecipher.doFinal(utf8);

            // Encode bytes to base64 to get a string
            return new sun.misc.BASE64Encoder().encode(enc);

        } catch (BadPaddingException e) {
        } catch (IllegalBlockSizeException e) {
        } catch (UnsupportedEncodingException e) {
        } catch (IOException e) {
        }
        return null;
    }

    public String decrypt(String str) {

        try {

            // Decode base64 to get bytes
            byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

            // Decrypt
            byte[] utf8 = dcipher.doFinal(dec);

            // Decode using utf-8
            return new String(utf8, "UTF8");

        } catch (BadPaddingException e) {
        } catch (IllegalBlockSizeException e) {
        } catch (UnsupportedEncodingException e) {
        } catch (IOException e) {
        }
        return null;
    }

    public static void main(String[] args) {
//        encryption phase
        String keyPhase = "my special phase";
        testUsingPassPhrase(keyPhase);
    }
}
